It has been known that sulfur vulcanized elastomers containing polar groups can be devulcanized with microwave energy as shown by the following U.S. Pat. Nos. 4,104,205 to Novotny, et al, 4,129,768 to Anderson, and 3,777,095 to Muranaka. These patents describe the operating parameters and equipment to which this invention is applicable and useful for devulcanization step. In commercial practice it has been learned that use of powdery partitioning agent, such as powdery silica to coat the particles and a fused quartz tube gives improved results and longer life to the tube.
Unfortunately, the devulcanized particles have relatively large amounts of fines and give off offensive fumes or vapors. Further, the temperature of the devulcanized material as it leaves the microwave devulcanizer is very high, usually in excess of 250.degree. C. and sometimes even in excess of 350.degree. C. and thus problems are experienced in handling and storing the devulcanized material. For instance, the hot particles from the devulcanizer can destroy a belt conveyor in a relatively short time and fills the air with carbon black fines and fumes.